A Computer network is a collection of computers and devices interconnected by communications channels that facilitate communications. A computer network may allow sharing of resources and information among interconnected devices. A network may include the Internet, an intranet, and the extranet.
A local area network (LAN) is typically a small network constrained to a small geographic area. A metropolitan area network (MAN) is typically a network constrained to metropolitan area, such as a city. A wide area network (WAN) is typically a network that covers a large geographic area. Wireless LANs are typically the wireless equivalents of LANs and WANs.
Networks may be interconnected to allow communication with a variety of different kinds of media, including twisted-pair copper wire cable, coaxial cable, optical fiber, power lines and various wireless technologies. A network may include routers and routing protocols.